In recent years, displays of image display devices including television receivers are shifting from conventional cathode-ray tube displays to thin-screen displays including liquid crystal panels and plasma display panels. With the thin-screen displays, thin image display devices can be provided. A liquid crystal display device requires a backlight unit as a separate lighting device because a liquid crystal panel used therein is not a light-emitting component.
A technology to provide thin and large-screen liquid crystal display devices is disclosed in Patent Document 1. A backlight disclosed therein includes LEDs and light guide plates. Each LED has a light emitting surface through which light is emitted in the direction substantially parallel to a display surface of a liquid crystal panel. Each light guide plate has a light entrance surface in a side area (a side-edge area) and a light exit surface on a top surface. The light entrance surface faces the LED and light from the LED enters the light guide plate through the light entrance surface. The light exits from the light exit surface toward the display surface of the liquid crystal panel. The light guide plates and the LEDs are arranged in parallel rows. Reflection layers are formed on opposed surfaces of the adjacent light guide plates. The reflection layers reflect light inside the light guide plates and guide it to the light exit surfaces.    Patent Document 1: Japanese Published Patent Application No. 2006-108045